274 



H. MOHN. METEOROLOGY. 



[nORW. POL. EXP. 



WIND-DIRECTION. DIURNAL PERIOD. 



In order to find the diurnal period of the wind's direction, it is necessary to 

 have a long series of observations for discussion. This I have sought to obtain 

 by collecting the numbers in the last table into the three following larger groups: 

 1, the dark season, comprising the months of October to February, during which 

 the sun was altogether below the horizon, or — at the beginning and the end 

 — only a short time above the horizon, but very low; 2, the sunny season, 

 comprising the months of April to August, in which the sun was above the horizon 

 during 24 hours; and 3, the equinoctial months March and September, in which 

 there was regular day and night. 



The following 3 Tables give the numbers belonging to these 3 groups. 



WIND-FREQUENCY. DARK SEASON. OCT.-FEBR. 15 MONTHS. 



